The story

There are more new cases of Americans infected with HIV, the virus that causes AIDS, than previously believed, the Centers for Disease Control and Prevention said Saturday.

About 56,000 people became infected with HIV in the past year, which translates to about 40 percent more cases than officials had estimated, said Dr. Kevin Fenton, director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention.

Previous CDC estimates suggested about 40,000 new people were infected each year. But those estimates used "limited data and less precise methods," said the center, which is now using technology capable of determining when someone was infected.

The new method can indicate whether someone has been infected with HIV during the previous five months, rather than relying on statistical models.